In recent years, many of light emitting elements used for displays and the like have a structure in which a layer containing a light emitting substance is interposed between a pair of electrodes. Such light emitting elements emit light when an exciton that is generated by recombination of an electron injected from one electrodes and a hole injected from the other electrodes returns to a ground state.
In order to obtain a light emitting element having an excellent light emitting efficiency and good chromaticity or a light emitting element that can prevent optical quenching and the like, various researches about substances that can be used as materials for manufacturing such a light emitting element have been carried out in the field of light emitting elements.
For example, the patent document 1 discloses a material for an organic EL element having an excellent light emitting efficiency and long term durability.
Meanwhile, in a light emitting element, a current flows between electrodes by transportation of holes or electrons. In this case, a light emitting substance that receives holes or electrons or the like, or, a light emitting substance that is oxidized or reduced or the like sometimes does not return to a neutral state and is changed to a different substance having a different property and a different structure. When the changes of the property and structure of the light emitting substance are accumulated, a characteristic of the light emitting element may also be changed.
Therefore, there are high expectations for a development of a light emitting substance of which a property is difficult to be changed due to oxidation or reduction.
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-131541.